View Full Version : FAQ for the basics?

10-25-2006, 01:13 PM
You know what would be really great, a faq for electronics basics. Stuff like the relationship between amperage and wattage and all those little formulas. I'm sure most of you guys can spout some of this stuff off the top of your head, but for a guy like me who hasn't had any electronics in 8 years and went to a liberal arts college....

10-25-2006, 01:52 PM
You can probably find a slew of them on the internet but the following would be the most basic of the basic.

Volts = I x R (I don't remember why but I stands for current - in otherwords Amps)

Power = V x I ( Power is measured in Watts)

From here you just use basic math to get whatever you want.
Since V=IR then V/R = I or V/I = R
You can then substitute these in the power formula
Power = V x V/R to give (VxV)/R or V^2 /R
Power = IR x I to give I^2 x R

Resistors in Series Add while resistors in parallel follow the inverse.
IE in Series R total = R1+R2+R3+...
in Parallel 1/Rtotal = 1/R1+1/R2+1/R3 ... and the final result for the resitance should always be lower than the lowest value of the resistors in parallel.

Series is where the current flows through all of the resistors and parallel is where the current splits among the resistors. I tried to give an illustration but it got all wacked when the format changed from the entry box to the forum listing so you can look for an example using google if you don't remember.

Capacitors are the same formula but just reversed.
Series is 1/C= 1/C1+1/C2+1/C3......
Parallel is C=C1+C2+C3

Capacitors and Inductors get into inductive and capacitive loads. Formulas can involve imaginary numbers relating to phase shifts and is less intuitive (at least to me than resistive ciruits)

These are the basic fundamentals without going into Kerchoffs rule or other ones related to circuits.

10-25-2006, 02:24 PM
These two sites have served this old diesel mechanic very well.



jonny's links page has an ohm's law calculator at the bottom. :)

Jon Gerow
10-25-2006, 03:39 PM
Things like these, I'll just add to the links page.

When the information is out there, I hate "stealing it" by copy and paste, but I will certainly link up good information. ;)

10-27-2006, 12:08 PM
There may be better sites that cover basic theory on electricity and electronic theory but I found this one when I did a quick google. It seems to cover the basics quite well although there appear to be some sections of "The first eleven" that are missing. The home page is http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm

Some people may find the newsgroups faqs found at http://www.repairfaq.org/ interesting. A quick glance shows that some of the information may be quite old (but basic physics never changes - just the application of it's principles).

I may be showing my age here but I feel that something is being lost nowadays. The internet used to be quite a resource of information. While dial up was slow at least most of the time you could find and download information and the newsgroups were top rate. The faqs that were created edited and available gave you a small number of places to look and find basically peer reviewed, clear and concise information. With broadband and the explosion of sites it is now somewhat overwhelming and frustrating to find the information that one wants and the newsgroups do not seem as active or rich as they once were (what used to be there seems to now be divided among thousands of forums on thousands of web sites - I know the irony that this is being posted in one such forum) . You use a search engine and get thousands of hits and then have to refine the terms but still end up with either no results or hundreds. To make matters worse when you start looking at them you find that the site doesn't have the information you want as they just put the search terms in to get higher hit ratings in google etc or they want you to register before you can look at the information. After you do this you usually find that it is not what you wanted or inaccurate or trivial. (I keep three e-mail addresses - one for all these sites, and you can just imaginge the spam in that one, one for internet desired sites like purchases and a final one that is for my friends and family). Then there are the sites that want to charge you for data that is available for free from other sources on the internet (IE driver sites). Useful sites come and go so quick that sometimes one is tempted to download whole sites just so that they can have access to that information and not have it lost. An example of this is a site that I had found about ten years ago. I believe it was "the informationculdesac" . It was based out of Winnipeg. I had found that the person who had created it had created a most wonderful resource of links on the web. It was the first place I ever found out that one could look up the manufacturer of devices by the UL number found on them. It had links to reverse telephone number searches that seemed to work and didn't want money for the information. There were links to almost every kind of information that one would be interested in and organized in a most useful format. One day when I tried to access the site it was no longer. A true loss. While I am not a true blue "information wants to be free" fanatic I believe that we are on the slippery slope of information=power=$ , which will leave the common person locked out from useful information while at the same time swamped with junk.

10-28-2006, 03:13 PM
The above liink while good is rather simplified. The following contains course level information that goes well beyond the basics. Once again there may be better sites and leave it for others to point them out.

These four books are from the Department of Energy and cover the gamut.





The following site starts with a list that you can choose individual sections on to test your knowledge. They are questions with answers later on. At the bottom of the page are actual courseware material complete with questions and answers to help clarify the actual course material.


I will search no further as these links cover basic info or refresher data to complete courses that prepare one to be an electronic technician.

10-29-2006, 02:34 PM
I like that last link talc. :) (ibiblio)

Slart, check out the tutorials at top center http://www.uoguelph.ca/~antoon/index.htm
The Mrs. Field's Cookies recipe on the left is worth a look. ;)

Sorry for a broken link. I deleted it.

10-29-2006, 05:07 PM
Back in the day it was like this: Wattage = Voltage multiplied by Amperage divided by resistance or in the case of AC impedance.

To find the numbers for voltage or amperage you can just move the numbers around assuming that you know at least three of the four numbers. If you needed to know the voltage you could divide the wattage by the amperage and then multiply it by the resistance...

God I miss high school.

10-29-2006, 07:34 PM
I like that link as well GY. While not truly so, it is close to using the Socratic Method for teaching (which is very difficult with written material) which I think helps with retention of learned material. The others I listed are disertations, which can get rather dry. I like the sites that you listed because they have actual projects and circuits which helps to actually illustrate what you can do with the theory.

11-12-2006, 09:17 PM
can you explain LaPlace Transforms and Fourier analasyst.

Jon Gerow
11-12-2006, 09:30 PM
Can you explain not using a question mark? Har har har!!

I'm not into functional analysis. If you're serious, maybe start a new thread and Super Nade might have some insight (no promises.) :D

11-12-2006, 10:43 PM
can you explain LaPlace Transforms and Fourier analasyst.

What do you want to know specifically? I might be able to help on something like frequency response, but we haven't covered much more than that in my class yet.

11-18-2006, 09:55 PM
Mainly about FFT ( fast fourier transforms)?